I listened to more of the PSS meeting this afternoon. In that portion of the meeting, it became clear that the largest single hit to the planetary program was in new technology development for Mars missions. The new technology program produces the engineering capabilities that enable the next generation of Mars missions. This would include projects to develop more precise landing capabilities (= opening up more of Mars to exploration since smaller safe areas could be targeted that lie within or near otherwise unsafe landing areas), new rover technology that would enable midsized rovers (in between MER and MSL in both capabilities and cost), and Mars sample return technologies among what is probably a longer list.
It was pointed out that by cutting these projects, the Mars program will be impacted for years (15 was mentioned) into the future. NASA simply won't have the technologies it was counting on ready in time for the post-MSL generation of (at least landed) Mars missions.
MSL will be a hell of a mission, and one that I think will be good science for the dollar. We just need to realize that the price of making those dollars available will be felt for a long time